Lighting control

[mk2phil]

Hi there,

I'm planning to buy a scenestyle 4 curcuit dimmer (http://www.scenestyle.co.uk/technical.html) to use with lots of small (20W - 50W) ELV halogen downlights in our living room.

I've bought a downlighter with a 35W MR8 bulb and a dimmable transformer to try out. When I tried it, the transformer was buzzing quite a lot and the light was flickering ever so slightly. I dont know if the current dimmer i'm using to test is leading/trailing edge as I've read that this can cause problems.

The scenestyle dimmer that I'm planning on buying is trailing edge - so does that mean I need to match this to trailing edge dimmable transformers in order to avoid the buzzing when the lights are dimmed?

[/url]

 

[Space cat]

That link doesn't work for me. It just says that the web page cannot be found so I can't get the info on your dimmer. I can only give you some general comments:

1) If your transformer is buzzing, it might be a real transformer. Real ones are dimmable. They are also heavy so that might be a clue. Unfortunately, a dimmer changes the nice, smooth sine wave into a series of short, sharp spikes. These are loaded with high order harmonics which tend to make transformers buzz. It doesn't matter whether the dimmer is leading or trailing edge either.

2) Trailing edge dimmers will not always work reliably with too light a load. Their internal circuitry fires a triac part way through each half-cycle but it will not stay on if the current is too low. You are planning to run many bulbs from your dimmer so it might be underloaded with just one.

3) You shouldn't really dim halogen bulbs. They don't like it. The envelope has to be hot enough for tungsten halide to form. This breaks down on the filament, thereby returning the tungsten to where it belongs. If you run one dim, two things can happen: the envelope becomes darkened with tungsten metal and the halogen strips tungsten off the filament instead.

 

[ColJack]

take the bracket off the end of the link.. it's not supposed to be there..

some dimmers have a minimum load as well as a maximum..

 

[mk2phil]

ok fixed the link guys.

So should I match trailing edge dimmer switches with trailing edge 'transformers'?